$5ef - 7eg + e + 10 = 9f + 4$ Solve for $e$.
Answer: Combine constant terms on the right. $5ef - 7eg + e + {10} = 9f + {4}$ $5ef - 7eg + e = 9f - {6}$ Notice that all the terms on the left-hand side of the equation have $e$ in them. $5{e}f - 7{e}g + 1{e} = 9f - 6$ Factor out the $e$ ${e} \cdot \left( 5f - 7g + 1 \right) = 9f - 6$ Isolate the $e$ $e \cdot \left( {5f - 7g + 1} \right) = 9f - 6$ $e = \dfrac{ 9f - 6 }{ {5f - 7g + 1} }$